I am trying to build a basic terminal server for 5-10 people. Since it's not mission critical I thought I'd forego spending £1500+ on a Dell or HP and just build it my self.

The case is a Supermicro CBL-0084L 1U

Motherboard is Asus P5G41T-M LX with 8GB RAM

Adaptec 2405 SAS PCIe card with 2 x 146GB Seagate Cheetah

However, I ran into a major problem from the very beginning; when the power is pressed, the CPU fan spins, the fans spin, the motherboard light is on but there’s no bleep from the machine nor is there any video.

I have spent several days trying to find out why. If I lift the motherboard out of the case then it works fine (9/10 times), and if I put it down in the case without screwing it in, it seems to work. The problem is when I screw the motherboard in; it starts to work/not work intermittently. So what I did was using electrical tape I taped the whole area beneath the motherboard, and some extra for overlap. I cut around the mounting holes for the screws. Now it works. But when I start screwing it in, it stops working, I’ve sort of found that if I put the screws in to the screw holes on the motherboard nearest to the peripheral ports and lift up the other edge of the motherboards, it boots OK. So, tried taping over the other unused screw points, thinking if they don’t touch the motherboard it should be fine. But alas, no, even with the tape covering the unused mounting points, it still doesn’t work unless I lift up the motherboard along one edge.

I bought a second different motherboard, but that doesn’t work at all, even outside the case.

How do I fix this? I know it’s a desktop board, but surely server cases aren’t designed to have the base of the motherboard closer to the metal underneath?

6 Replies

it does sound like some kind of short, although as long as the case is rated for the type of motherboard (AT/ATX) than it should be fine. Maybe the case is bent and is flexing the motherboard?

One thought I have, a lot of cases come with screw risers (for lack of better terminology). They are posts that screw into the case and then the motherboard screws into them. If the case came with there and you did not use them, that would cause issues.

If you're not using the rise screws on the motherboard mounting tray, that would cause the short.

If you are using the riser screws it could be one of two things.

1.) A broken trace on the MB.
When the corner of the MB is lifted, the break is closed and the MB will power up.
Use a magnifying glass to locate the broken trace(s) scrape the coating off the trace on either side of the break and solder a wire to both sides of the trace to repair the break.

I am definitely using the riser screws for all 6 screw points on the motherboard.

I'll check the trace, but surely when the motherboard is lifted, the break could not be closed, isn't it more likely that the opposite is happening; two or more points on the underside are coming into contact with the base of the case?

I'll try a different case, unfortunately I was hoping to get this working by Monday, but it looks like it'll have to wait. Thanks guys.

I am definitely using the riser screws for all 6 screw points on the motherboard.

Good

Aziz5838 wrote:

I'll check the trace, but surely when the motherboard is lifted, the break could not be closed, isn't it more likely that the opposite is happening; two or more points on the underside are coming into contact with the base of the case?

If a trace is broken, when you lift the board it would bend a little forcing the break in the trace closed. Chances are, there is no break in any trace. Most likely it's a grounding issue with the case or power supply.

I have seen issues where the case was built incorrectly and the whole chassis had to be replaced with one without the grounding flaw.